PHP Freaks

Note: This post is not a tutorial! If you have any questions related to underlying concepts, I can recommend my tutorials [/profile/448191] and the Application Design board [/forums/index.php/board,58.0.html].

Like it or not, as a professional developer, sooner or later you are going to do some customising (if you are lucky, "extending") of existing software.

If you are not familiar with the software, it is good advice to look into it before accepting the job. I had to learn that the hard way. But how do you recognize crappy applications without getting knee deep into the code? 10 pointers to identify crappy PHP software quickly...

1. The software tries to reinvent the object model, or "fix" language features.

See if you can find a class called "Object". If you find it, it's a pretty clear indication that the author is in the business of trying to reinvent the object model (most commonly because of his own lacking understanding of OO). It is safe to assume that his "fixes" won't stop there. Unplug your phone and hide under your desk.

2. The code includes user defined global variables

A search in the code for "global" or "$GLOBALS" may reveal something like this:

global $database, $my, $mainframe;

The infamous global variable. If you can tell me what those last two variables contain you are either intimate with the software I pulled it from, or you're psychic. Unlimited bonus points if you can say what code has had it's claws on it before execution flow got to this point. In short, steer well clear.

3. Scattered HTML and SQL

Search for some common SQL and HTML strings. You should be able to determine very quickly whether these are appropriate places for HTML or SQL. If you find HTML and SQL in the same file, "crappyness" is most definitely confirmed.

4. Classes do too much

Find the 3 largest class files by bit size. Take a look at the class name. Does it indicate a distinct responsibility? Look at the methods. Are the tasks they perform closely related? If not, run away screaming.

5. Lots of properties are public or lots of properties are static

If lots of properties are declared "public static", triple your quote. If I have to explain why, maybe there's an open position on the development team of the software for you.

6. Multiple levels of inheritance

More than 2 levels inheritance should be avoided like the plague. I stake my life on the resulting objects having too much unrelated behaviour (ok, maybe not my life, but if you find a proper use of more than 2 levels of inheritance, I'll buy you a beer).

7. The authors try to use Design Patterns

Whether or not the authors have a clue is easily determined by searching for some of the most common design patters. Search the code base and/or documentation for "factory", "decorator", "strategy" etc. If present, you can pretty quickly determine whether the authors know their stuff or are trying to look interesting. That is, if you know how the code should look. If not, refuse to take the project until you do.

8. The software messes with the error level

Well written applications run fine at any error level. Searching the files for /error_level\(.*\)/ should do the trick. In case of hits, try replacing the value with E_STRICT. That's little more than a formality though.

9. In the code base, there is a directory called "core"

This is usually used as an excuse to have the whole application dependent on whatever is in there. Despite the appeal of the term (it does make the contents sound pretty cool and important), defining a "core" is a sign of bad design.

10. The software uses it's own template language.

Be afraid. Very afraid. These guys are definitely in the business of reinventing the wheel. Ignore this warning and you will find yourself spending the better part of a day simulating a "for" loop.